Gene Circuit and Parts

Used and Characterized Pre-Existing Parts

1. Experience - Promoter (LuxR/3OC6-HSL regulated), BBa_R0062: the promoter's EC₅₀ could be shown to be dependent on the amount of regulator LuxR (BBa_C0062) in the system by using the three different constitutive promoters BBa_J23100, BBa_J23109, and BBa_J23111 for the production of LuxR. The amount of regulator also demonstrated an influence on the promoter's basal expression or leakiness. Additionally, it could be determined that the promoter can also be activated by the regulators LasR (BBa_C0179) and RhlR (C0171) thus showing crosstalk with these two quorum sensing systems.
   
   
2. Experience - Promoter (LasR/3OC12-HSL regulated), BBa_R0079: it could be shown that this promoter, which is usually activated by the regulator LasR (BBa_C0179) can also be activated by the regulators LuxR (BBa_C0062) and RhlR (C0171). Therefore, it shows crosstalk with these two quorum sensing systems.
   
   
3. Experience - Promoter (RhlR/C4-HSL regulated), BBa_I14017: the amount of regulator RhlR (C0171) demonstrated an influence on the promoter's basal expression or leakiness as well as on the steepness of the response. This was investigated using two different RBSes controlling the expression level of RhlR, i.e. the RBS B0034 and a RBS optimized for rhlR using the Salis Lab RBS Calculator^[13].
   
   
4. Experience - Regulator LuxR, BBa_R0062: it could be shown, that the regulator LuxR not only activates the promoter BBa_R0062 together with 3CO6-HSL, the product of the enzyme LuxI (BBa_C0161), but also with 3CO12-HSL (LasI (BBa_C0178) product) and C4-HSL (RhlI (BBa_C0170) product).
   
   
5. Experience - Regulator LasR, BBa_C0179: it could be shown, that the regulator LasR activates the promoter BBa_R0079 mainly together with 3CO12-HSL, the product of the enzyme LasI (BBa_C0178) and only to a minor extend with 3CO6-HSL (LuxI (BBa_C0161) product) and C4-HSL (RhlI (BBa_C0170) product).
   
   
6. Experience - Regulator RhlR, BBa_C0171: it could be shown, that the regulator RhlR not only activates the promoter BBa_R0071 together with C4-HSL, the product of the enzyme RhlI (BBa_C0170), but also with 3CO6-HSL (LuxI (BBa_C0161) product) and 3CO12-HSL (LasI (BBa_C0178) product), while the ladder is acting least activating among those three AHL molecules.
   
   
7. Experience - Promoter, BBa_J23100: the constitutive promoter BBa_J23100 was compared to the promoters BBa_J23109 and BBa_J23111 by placing each in a construct in front of the quorum sensing regulator LuxR (BBa_C0062). The system behaved as expected, thus confirming an increasing promoter strength from BBa_J23109 over BBa_J23111 to BBa_J23100.
   
   
8. Experience - Promoter, BBa_J23111: the constitutive promoter BBa_J23111 was compared to the promoters BBa_J23109 and BBa_J23100 by placing each in a construct in front of the quorum sensing regulator LuxR (BBa_C0062). The system behaved as expected, thus confirming an increasing promoter strength from BBa_J23109 over BBa_J23111 to BBa_J23100.
   
   
9. Experience - Promoter, BBa_J23109: the constitutive promoter BBa_J23109 was compared to the promoters BBa_J23100 and BBa_J23111 by placing each in a construct in front of the quorum sensing regulator LuxR (BBa_C0062). The system behaved as expected, thus confirming an increasing promoter strength from BBa_J23109 over BBa_J23111 to BBa_J23100.
   
   
10. Experience - Autoinducer synthetase for the AHL molecule 3OC6-HSL, BBa_C0161: by placing an alginate bead into a millifluidic chip containing sender cells, which are constitutively expressing LuxI (BBa_C0161) in vicinity to a bead containing receiver cells with a construct producing sfGFP in presence of 3OC6-HSL it could be shown that signal transduction was successful. Thus it could be confirmed that the synthetase is producing a quorum sensing molecule.

Our Favorite New Characterized Parts

1. Main Page - sfGFP under Riboregulated Promoter (RhlR/C4-HSL, RR12), BBa_K1541009: this part contains the same riboregulated promoter system as the part BBa_K1541009 succeeded by the gene for sfGFP. This construct was used to characterize the properties of the riboregulated quorum sensing promoter BBa_K1541009 and can be used in a C4-HSL sensor where low leakiness is desirable.
   
   
2. Main Page - rhlI with optimized RBS, BBa_K1541017: this part is similar to the part BBa_I9026, but contains instead of the RBS BBa_B0034 a RBS which was specifically optimized for rhlI (C0170) using the Salis Lab RBS Calculator^[13]. With higher levels of RhlI, the production of the enzyme's product C4-HSL can be improved.

Characterized New Parts

1. Main Page - Riboregulated Promoter (LuxR/3OC6-HSL, RR12y), BBa_K1541000: this riboregulated promoter construct contains the quorum sensing promoter BBa_R0062 which can be activated in presence of LuxR (BBa_C0062) and 3OC6-HSL, which is the product of the enzyme LuxI (BBa_C0161). However, the original promoter by itself shows high leakiness. Together with the ribogegulator 12y^[18] the leakiness could be reduced by almost two orders of magnitude and the ON/OFF ratio increased approximately 6 times.
   
   
2. Main Page - sfGFP under Riboregulated Promoter (LuxR/3OC6-HSL, RR12y), BBa_K1541006: this part contains the same riboregulated promoter system as the part BBa_K1541000 succeeded by the gene for sfGFP. This construct was used to characterize the properties of the riboregulated quorum sensing promoter BBa_K1541000 and can be used in a 3OC6-HSL sensor where low leakiness is desirable.
   
   
3. Main Page - Riboregulated Promoter (RhlR/C4-HSL, RR12), BBa_K1541003: this riboregulated promoter construct contains the quorum sensing promoter BBa_R0071 which can be activated in presence of RhlR (BBa_C0171) and C4-HSL (the product of the enzyme RhlI (BBa_C0170)). However, this promoter by itself shows some leakiness. Together with the ribogegulator 12^[18] the leakiness could be reduced.